src/pytz/__init__.py | 15 13 + 2 - 0 !
src/pytz/tzfile.py | 3 2 + 1 - 0 !
2 files changed, 15 insertions(+), 3 deletions(-)

 use system zone information from the tzdata package

src/pytz/__init__.py | 128 128 + 0 - 0 !
1 file changed, 128 insertions(+)

 dynamically determine list of available and common timezones

The Debian/Ubuntu packages of pytz include a patch to not install pytz's
zoneinfo database and instead load data from the system zoneinfo
database. This keeps pytz up to date when system timezone updates are
installed which is generally a good idea.

The `pytz/__init__.py` includes `common_timezones` and `all_timezones`
lists, which enumerate the time zones in the database pytz was released
with. If pytz is instead using the system database, these lists may not
be correct (e.g. missing newly added time zones).

Dynamically determine `all_timezones` and `common_timezones`. For
`all_timezones` use `zoneinfo` from Python 3.9 and for
`common_timezones` parse `/usr/share/zoneinfo/zone1970.tab`.

Bug: https://launchpad.net/bugs/207604

src/pytz/__init__.py | 12 11 + 1 - 0 !
src/pytz/tests/test_tzinfo.py | 60 30 + 30 - 0 !
2 files changed, 41 insertions(+), 31 deletions(-)

 determine iana (nee olson) database version dynamically